1. Field of the Invention
The field of the invention is dielectric optical cable.
2. Background of the Invention
Fiber optic transmission systems are becoming more and more common in actual usage in today's communication requirements. In order to take full advantage of fiber optic technology, optical cables are needed which correspond to the familiar drop cables of the copper cable industry: i.e., a cable which connects the general loop to an individual subscriber residence. Typically, such cables are required to meet Underwriters Laboratories' VW-1 (Vertical-Wire) flame propagation requirements because the cable is designed to be attached to the outside of a residence.
Because the cable must also be installed outdoors, the usual requirement is that the cable be filled with waterblocking compounds (typically greases) so that water does not travel longitudinally through the cable.
U S. Pat. No. 4,743,085, issued May 10, 1988, is incorporated herein by reference. Disclosed therein is a dielectric fiber optic cable in which the optical fibers are disposed in a waterblocking material. While the waterblocking material tends to keep water away from the optical fibers, such waterblocking materials are typically flammable.
The Article, "A High Performance Non-Metalic Sheath for Light Guide Cables," published on pages 344-349 of the 1987 International Wire and Cable Symposium Proceedings discusses a cable which is believed to be the same as that disclosed in U. S. Pat. No. 4,743,085. The magazine article discloses that a second fire resistant cable is also available. This fire resistant cable does not contain a filling compound.